Scanning electron microscope

ABSTRACT

An object of the present invention is to provide a scanning electron microscope for reducing a process concerning inspection positioning or an input operation, thereby functioning with high precision at high speed. To accomplish the above object, the present invention provides a scanning electron microscope having a function for identifying a desired position on the basis of a pattern registered beforehand, which includes a means for setting information concerning the pattern kind, the interval between a plurality of parts constituting the pattern, and the size of parts constituting the pattern and a means for forming a pattern image composed of a plurality of parts on the basis of the information obtained by the concerned means.

This is a continuation of application Ser. No. 10/615,864 filed 10 Jul.2003, which is a continuation of appliction No. 09/792,721 filed 23 Feb.2001, the contents of which are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scanning electron microscope and moreparticularly to a scanning electron microscope for suitably executingpositioning to an inspection position on a semiconductor integratedcircuit.

2. Discussion of the Background

In correspondence to recent integration of semiconductor devices, ascanning electron microscope is used for observation and inspection of arefined circuit pattern. A scanning electron microscope (hereinafterreferred to as CD-SEM) for measuring the size of a specific pattern usedon the semiconductor manufacture line is promoted in automation so as toprevent raising of dust by a person in the same way as with otherdevices or to improve the processing capacity.

In order to automatically measure a target pattern on a wafer, aprocedure of moving the observation view field to an approximateposition by stage movement, precisely obtaining the measuring patternposition from the observation view field, moving the view field to theposition, and measuring the pattern is used. To execute automaticoperation, the aforementioned sequence is stored as a file (hereinafterreferred to as a recipe file) and at the time of automatic operation,the recipe file is read and the sequence is executed automatically. Todetect the precise position of the measuring pattern, the image part(hereinafter referred to as a template) including a characteristicpattern as a guide is registered beforehand and the position is decidedby the distance from the pattern position detected by template matching.

In Japanese Patent Application Laid-Open 9-245709, an art forregistering a template as a guide beforehand and deciding the targetmeasuring pattern position by matching using the template is disclosed.

SUMMARY AND OBJECTS OF THE INVENTION

A problem as indicated below is imposed in inspection positioning of asample by the template matching method.

Firstly, to execute template matching, as mentioned above, it isnecessary to register a template as a guide beforehand. However, toregister a template for template matching, it is necessary to set anenvironment for introducing and observing a sample such as asemiconductor wafer into a sample chamber. Further, to search for apattern as a template, a considerable time is required.

In actual positioning by template matching, a normalization correlationvalue is obtained for the front of an image including a registeredpattern and an image to be detected, so that the portion having noinformation in the template and the noise portion are also calculated.As a result, an incorrect position may be detected due to noise,charge-up of a sample, or uneven contrast.

An object of the present invention is to provide a scanning electronmicroscope for reducing a process concerning inspection positioning oran input operation, thereby functioning with high precision at highspeed.

The present invention, to accomplish the above object, provides ascanning electron microscope having a function for detecting a patternon the basis of electrons obtained by scanning an electron beam on asample and identifying a desired position on the basis of the detectedpattern and a pattern registered beforehand, which is characterized inthat the microscope has a means for setting information concerning thepattern kind, the interval between a plurality of parts constituting thepattern, and the size of parts constituting the pattern and a means forforming a pattern image composed of a plurality of parts on the basis ofthe information obtained by the concerned means.

By use of such a constitution, a template can be registered withoutsetting an observation environment of a scanning electron microscopesuch as evacuation. Particularly, with respect to a pattern having aproperly regulated arrangement like a line pattern or a hole patternformed on a semiconductor wafer, if there is information for identifyingthe size of a plurality of parts forming the pattern and the relativeposition relationship available, the pattern image can be identified.

The present invention takes up this point, has a constitution ofselectively inputting a necessary condition, and forms a pseudo-patternon the basis of it, so that conventional image forming using an actualpattern image is unnecessary and the operation time can be contractedgreatly.

Furthermore, the present invention, to accomplish the above object,provides a scanning electron microscope having a function for detectinga pattern on the basis of electrons obtained by scanning an electronbeam on a sample and identifying a desired position on the basis of thedetected pattern and a pattern registered beforehand, which ischaracterized in that the microscope has a means for recognizing thenumber of detected patterns and/or the interval between a plurality ofparts of the detected patterns, a means for calculating the evaluationvalue on the basis of comparison of the number recognized by theconcerned means with the number of registered patterns, and/or a meansfor calculating, on the basis of comparison of the interval recognizedby the means with the interval between the parts of the registeredpatterns, the evaluation value based on the consistency.

For example, when a pattern composed of a plurality of parts (linepatterns or hole patterns) is crushed and the line patterns or the holepatterns are in contact with each other, the pattern is one that lengthmeasurement and inspection of the line or hole patterns are notnecessary and pattern matching is difficult. According to the presentinvention, when the number of line patterns and/or the interval arestructured so as to evaluate selectively, it can be judged whether eachpattern is suitable for length measurement and inspection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an embodiment of the present invention.

FIG. 2 is a drawing for explaining the registration sequence.

FIGS. 3A and 3B are drawings for explaining an example of a registrationscreen for registering form information and position information.

FIGS. 4A and 4B are drawings for explaining an example of a registrationscreen for registering form information and position information.

FIG. 5 is a drawing for explaining the steps for detecting a pattern.

FIG. 6 is a drawing for explaining the detection processing steps of animage processing unit.

FIG. 7 is a drawing for explaining the pattern form evaluationprocedure.

FIGS. 8A and 8B are drawings showing a display example of evaluationresults of form information and position information.

FIGS. 9A and 9B are drawings showing examples of a position relationshipimage and a position relationship mask of a hole pattern.

FIGS. 10A and 10B are drawings showing scan range examples of a holepattern.

FIGS. 11A and 11B are drawings showing scan range examples when ameasuring edge is to be detected.

FIG. 12 is a drawing showing an example that the scanning electronmicroscope of this embodiment is connected to a network.

FIG. 13 is a drawing showing the detection procedure of a hole pattern.

FIGS. 14A and 14B are drawings showing an example of a registrationscreen for registering hole pattern information.

DETAILED DESCRIPTION

With respect to an image obtained by the scanning electron microscope,many secondary signals are emitted from the pattern edge (edge effect),so that the information of the edge is main. The pattern edge in animage is extremely smaller in an area than the whole image, though itincludes most pattern information of a sample. Inversely, the part otherthan the edge has no pattern or includes much noise having littleinformation used for positioning.

A general template matching method identifies a pattern using thetemplate. However, the template matching method obtains a normalizationcorrelation value for a registered image portion and all images to bedetected, so that the part (part having no edge) having no informationin the template and the noise portion which is not information are alsocalculated. As a result, an incorrect position may be detected due tonoise, charge up, or uneven contrast.

Particularly, on the semiconductor manufacture line, in order to obtainmost suitable manufacture conditions (for example, stepper exposuretime, variations of the focus, etc.), a test wafer having conditionschanged for each chip (hereinafter referred to as a conditional wafer)is prepared.

CD-SEM is used for inspection of this conditional wafer. The pattern ofthe conditional wafer to be observed for each chip becomes a patterngreatly different in the pattern form as the manufacture conditions areshifted more from the most suitable manufacture conditions. Depending onthe conditions, a resist remains, and adjacent patterns are connected toeach other, and any pattern gets thin and comes down, and the number ofpatterns decreases. When the pattern form and count are changed likethis, it is difficult to detect them using the template matching method.

When the template is to be registered, it is necessary to actuallyobserve the sample pattern, form an image, and preserve the imageportion. For a conditional wafer, an operation of registering aplurality of templates is generated. To select a pattern as a guide ordecide a most suitable magnification factor, skill is required.Furthermore, decision of success or failure of detection is made only bya normalization correlation value.

Therefore, when the normalization correlation value is more than thethreshold value even if the number of patterns is changed, the positionhaving no existing pattern is measured.

The equipment of this embodiment of the present invention performs aprocess relating to template matching using information concerning thenumerical value of the pattern form and information concerning theposition relationship, thereby can solve the aforementioned problem.

The embodiment of the present invention will be explained hereunder withreference to the accompanying drawings.

FIG. 1 is a schematic view of the scanning electron microscope of thepresent invention. An electron beam 2 emitted from an electron gun 1 isdeflected by a deflecting coil 3, then limited thinly by an object lens4, and irradiated onto a sample wafer 5 on a stage 6. The object lens 4is controlled by an object lens control circuit 21 which can becontrolled from a host computer 13.

The scanning range and scanning position on the sample wafer 5 can bechanged by a deflecting signal which is generated by a deflecting signalgenerator 8, amplified by a deflecting amplifier 7, and supplied to thedeflecting coil 3.

Secondary electrons emitted from the sample wafer 5 by incoming of theelectron beam 2 is converted to an analog electric signal by a detector9, converted to a digital signal by an A-D converter 10, and then storedin an image memory 11. The contents of the image memory 11 are alwaysconverted from a digital signal to an analog signal by a D-A converter12 and applied to the grid as a luminance signal of a CRT 20. At thistime, the A-D converter 10, the image memory 11, and the D-A converter12 receive a timing signal for converting an image signal from analog todigital, further converting from digital to analog, and displaying it asan image from the deflecting signal generator 8.

A deflecting coil 19 of the CRT 20 is excited by a deflecting amplifier18 according to a deflecting signal of the deflecting signal generator8. The magnification factor is decided by the display width and scanningrange of the CRT 20. An image processor 16 is controlled by a signalfrom the host computer 13. The contents of the image memory 11 aretransferred and processed by an image memory + of the image processor16.

The sequence of the present invention for registering pattern forminformation (pattern kind, pattern height, width, etc.) and positionrelationship (interval between patterns, etc.) is shown in FIG. 2. FIGS.3A and 3B are drawings showing registration screen examples forregistering the form information and position relationship according tothe sequence shown in FIG. 2.

The host computer 13 displays a registration screen on the CRT 20according to a signal from a mouse 14 or a keyboard 15. There is a menu(301) for selecting the pattern kind on the screen and the line patternsand hole patterns can be selected (S2001).

A user inputs pattern information to an input window (302 a) of the linewidth Width (302), an input window (303 a) of the line length Height(303), an input window (304 a) of the line number Number (304), and aninput window (305 a) of the pitch Pitch (305) between line patternsrespectively from the keyboard 15 (S2002) and then presses an OK button(306). The host computer 13 obtains a magnification factor Mag (308)from Formula (1) on the basis of the values of (302) to (305).Furthermore, the host computer 13 prepares a pseudo-pattern (309) to bedisplayed on the image when it is observed at the obtained magnificationfactor and displays it on the CRT 20 as an image (307) together with Mag(308) (S2003). A display example is shown in FIG. 3(a). The userascertains the input value by the pseudo-pattern (309) (S2004). Whenthere is a contradiction, the user repeats the steps (S2001 to S2004).When there is no contradiction, the user inputs the threshold value ofnumber (311) Num.Accept. at the time of detection to an input window(311 a) (S2005) and presses a registration button (310). Upon receipt ofthis signal, the host computer 13 preserves the input information (302)to (305), the magnification factor (308), and the threshold value ofnumber (311) Num.Accept. in a storage unit 22 as a line detection file(312) in association with a recipe file 25 (S2006).1wp=min(Width, Pitch−Width)(nm)Mag.=1p min×rw/(pw×1wp)  Formula (1)

-   -   where 1wp: a smaller value between 1w and 1p-1 w,    -   rw: width of the image display area,    -   pw: width of a display image (pixel), and    -   1p min: minimum processing width (pixel).

A screen example (400) when holes are selected is shown in FIGS. 4A and4B. The user inputs pattern information to an input window (401) of thehole diameter Diameter, an input window (402) of the number in thedirection x (column) X-Num., an input window (403) of the number in thedirection y (row) Y-Num., an input window (404) of the pitch in thedirection x (column) X-Pitch, and an input window (405) of the pitch inthe direction y (row) Y-Pitch respectively from the keyboard 15 (S2002)and then presses an OK button (406). The host computer 13 prepares apseudo-pattern (409) on the basis of the values of (401) to (405).Furthermore, the host computer 13 obtains a magnification factor Mag.(408) by Formula (2) and displays it on the CRT 20 together with thepseudo-image (409) (S2003).

A display example is shown in FIG. 4A. The user ascertains the inputvalue by the pseudo-image (407) (S2004). When there is a contradiction,the user repeats the steps (S2001 to S2004). When there is nocontradiction, the user inputs the threshold value of number Num.Accept.at the time of detection to an input window (411) (S2005) and presses aregistration button (410). Upon receipt of this signal, the hostcomputer 13 preserves the input information (401) to (404) and themagnification factor (408) in the storage unit 22 as a line detectionfile (412) in association with the recipe file 25 (S2006).harea=max ((hnx−1)×hpx, (hny−1)×hpy)(nm)mag=rw/(harea×2)  Formula (2)

-   -   where harea: a larger value between (hnx−1)×hpx and (hny−1)×hpy        and    -   rw: width of the image display area.

The pattern form information and position relationship can be read via anetwork 120 connected to the host computer 13. The pattern forminformation and position relationship can be read from a storage unit121 of a file server and a storage unit 123 a or 124 a of a manufacturecondition file of a manufacturing device 123 or a manufacture conditionfile of another manufacturing device 124.

The sequence of the present invention for detecting patterns using thepattern form information and position relationship is shown in FIG. 5.The host computer 13 reads the recipe file 25 designated by the mouse 14or the keyboard 15 by a user from the storage unit 22 (S5001) and readsthe line detection file (312) (or the hole detection file (412)) inassociation with the recipe file 25 at the same time (S5002).

The host computer 13 sends a drive signal to the stage 6 from themeasuring position information registered in the recipe file 25beforehand and moves the stage 6 to the measuring position (S5003). Inthis case, the pattern form information and position relationship aretransferred to the image processor 16. The host computer 13 decides thescanning range on the sample wafer 5 according to the magnificationfactor (308) (S5004). The host computer 13 irradiates an electron beamonto the sample wafer 5 by a deflecting signal which is generated by thedeflecting signal generator 8, amplified by the deflecting amplifier 7,and supplied to the deflecting coil 3 on the basis of the scanning rangeand obtains an image in the image memory 17 according to theaforementioned procedure (S5005).

Upon receipt of a detection processing signal from the host computer 13,the image processor 16 executes the detection process (S5006) andreturns the number of detected patterns to the host computer 13. Thehost computer 13 compares it with the threshold value of number (313)(S5007) and when the number of detected patterns is larger than thethreshold value of number (313), the image processor 16 executes patternevaluation. The reason for that the pattern evaluation is executed whenthe number of detected patterns is larger than the threshold value ofnumber is that mixing of noise is taken into account. However, the imageprocessor 16 may be structured so as to execute evaluation only whenboth numbers are the same.

When the number of detected patterns is smaller than the threshold valueof number (313), the host computer 13 skips pattern evaluation andmeasurement. The image processor 16 executes pattern evaluationaccording to this instruction and returns the evaluation value to thehost computer 13. The host computer 13 compares it with the thresholdvalue of pattern evaluation of the recipe file 25 and decides whetherthe patterns can be measured (S5009). One condition of the evaluationthreshold value is the threshold value of number (313) explainedpreviously.

When the patterns can be measured, the host computer 13 detects themeasuring edge (S5100) and then measures the patterns (S5010) and whenit judges as unmeasurable, it skips measurement. By use of such aconstitution, unnecessary calculation and scan can be prevented and evenif the number of patterns is reduced in a stepper conditional wafer, thepatterns are detected and neighboring patterns which are connected toeach and must not be measured can be prevented from measurement, so thatuseless processes can be reduced and the processing speed can beincreased.

When the patterns are detected using the numerical information ofpattern form and the position relationship, patterns that the form isgreatly changed and the number of patterns is also changed likeconditional patterns can be detected. Furthermore, since the numericalinformation of pattern form and the position relationship are used, atemplate using an actual pattern image is not registered, so that theOFF line can be registered. Further, there is no need to select apattern as a guide requiring experience and numerical data is directlyinput, so that the registration operation can be simplified. Since theoperation is performed according to the threshold value input beforehandon the basis of the pattern evaluation value, the sequence can beoptimized.

When the aforementioned series of processes is finished, the hostcomputer 13 reads the next measuring position from the recipe file 15(S5011). The host computer 13 executes measurement from the mostsuitable measuring position on the basis of the information of themanufacture condition files from the manufacture devices 123 and 124.The next measuring position is decided on the basis of the number ofdetected patterns and pattern evaluation value. For example, the hostcomputer 13 judges the direction of the pattern form getting worse fromthe number of detected patterns and pattern evaluation value and doesnot move to the measuring position outside the measuring position wherethe number of detected patterns is smaller than the threshold value(S5012). By doing this, useless processes can be prevented fromexecution and the processing speed is increased.

The image processor 16 displays results on the image memory 17 using thedetected pattern position, pattern form information, positionrelationship, and mapping images. A display example of results is shownin FIG. 8. In the case of the line pattern, results are displayed as theline pattern image (800) shown in FIG. 8A. When the detected pattern islike (801), the evaluation value a of the mapping images correspondingto the respective line pattern positions obtained from the detectedpattern position is displayed like a graph (802). The height of each ofthe bar graphs indicates a ratio on the basis of the maximum value ofthe evaluation value a of the mapping images. In the case of the holepattern image (803), a cross mark (804) is displayed as shown in FIG.8(b). The difference in the evaluation value of each pattern isreflected in the size of the cross mark.

The detection process of the image processor 16 using the pattern forminformation and position relationship is shown in FIG. 6. The imageprocessor 16 prepares a pattern mask of the pattern form to be detectedfrom the pattern width (301) and pattern height (302) of the patternform information (S6001). The pattern mask is one pattern part shown inFIGS. 4(a) and 4(b). The image processor 16 calculates the evaluationvalue a by shifting the pattern mask in position overall the image ofthe image memory 17 (S6002) and prepares a mapping image that thecalculated evaluation a is arranged in correspondence with the patternmask position (S6003). The evaluation value a is calculated by Formula(3) or Formula (4) and Formula (5). $\begin{matrix}{{r\left( {X,Y} \right)} = \frac{\left\lbrack {{N{\sum\limits_{i,j}\quad{P_{ij}M_{ij}}}} - {\left( {\sum\limits_{i,j}\quad P_{ij}} \right)\left( {\sum\limits_{i,j}\quad M_{ij}} \right)}} \right\rbrack}{\sqrt{\left\lbrack {{N{\sum\limits_{i,j}\quad P_{ij}^{2}}} - \left( {\sum\limits_{i,j}\quad P_{ij}} \right)^{2}} \right\rbrack\left\lbrack {{N{\sum\limits_{i,j}\quad M_{ij}^{2}}} - \left( {\sum\limits_{i,j}\quad M_{ij}} \right)^{2}} \right\rbrack}}} & {{Formula}\quad(3)}\end{matrix}$

-   -   where P_(ij) indicates a density value at the point (X+i, Y+i)        corresponding to the pattern mask of the line pattern image        (800) or the hole pattern image (803), and M_(ij) indicates a        density value at the point (X+i+1, Y+j+1), and N indicates the        number of pixels of the pattern mask. $\begin{matrix}        \frac{{\sum\limits_{i}\quad{\sum\limits_{j}\quad{{P_{i,j} - P_{{i + 1},j}}}}} + {{P_{i,j} - P_{i + j + 1}}}}{N} & {{Formula}\quad(4)}        \end{matrix}$    -   where P_(ij) indicates a gradation value of the line pattern        image (800) or the hole pattern image (803) and N indicates a        total number of pixels of the pattern mask. $\begin{matrix}        \frac{\sum\left( {P_{ij} - P_{avg}} \right)^{2}}{N - 1} & {{Formula}\quad(5)}        \end{matrix}$    -   where P_(ij) and P_(avg) indicates mean values in the pattern        mask corresponding to the gradation value of the line pattern        image (800) or the hole pattern image (803) and N indicates a        total number of pixels of the pattern mask.

Next, the image processor 16 prepares a position relationship mask froma plurality of patterns (303) and position relationship (Pitch (304))(S6004). The line pattern position relationship image (901), the linepattern position relationship mask (902), the hole pattern positionrelationship image (90), and the hole pattern position relationship mask(90) corresponding to FIGS. 4A and 4B are shown in FIGS. 9A and 9B. Theimage processor 16 obtains the sum total of evaluation values a byshifting the position of the prepared position relationship mask on themapping image (S6005). The position where the sum total of evaluationvalues a is maximized is the position to be detected (S6006). Withrespect to the position relationship mask, in consideration of reductionof the number of patterns, the image processor changes the number ofpatterns by the number of patterns (303)˜the threshold value (311) andrepeats S6004 to S6006. By the aforementioned process, the number ofpatterns and the detection position can be obtained.

The evaluation procedure for the pattern form by the image processor 16is shown in FIG. 7. The image processor 16 selects the part having nopattern from the prepared mapping image prepared at S6003 (S7001). Withrespect to selection of the part having no pattern, for example, thehalf value of the maximum value of the mapping image is set as athreshold value and the part below the threshold value is selected. Thenoise level (for example, dispersion) of the part having no pattern iscalculated by Formula (5) (S7002).

Next, the image processor 16 detects the part where the pattern form iseasily changed from the position detected at S6006 and calculates thesignal level (for example, dispersion) obtained at S7003 (S7004). Thispart may be often set between patterns. The image processor 16 obtainsthe evaluation value b (SN ratio) from the noise level and signal levelobtained at S7002 and S7003 and returns it to the host computer 13. Alsofor the hole patterns, the pattern position, number of patterns, andevaluation value b can be obtained according to the same procedure.

An embodiment that the electron beam scanning range is changed frominput information in accordance with the pattern form will be explainedhereunder. This process is used to receive a signal from a part wherethe pattern form is easily changed (S7004) or to detect a measuring edge(S5100). To receive a signal from a part where the pattern form iseasily changed, the host computer 13 decides the scanning range usingthe position, line width (302), and pitch (305) which are detected asS6006 (in the case of the hole pattern, the hole diameter (401) andpitches in the directions x and y (404) and (405)). The scanning rangeexamples of the line pattern and hole pattern are shown in FIG. 10.

Assuming that the measuring pattern is (1001) in the line pattern image(1000), the evaluation scanning range is the position of (1002).Assuming that the measuring pattern is (1004) in the hole pattern image(1003), the evaluation scanning range is (1005). When the scanning rangeexample of detection of a measuring edge is shown in FIG. 11. Assumingthat the measuring pattern is (1101) in the line pattern image (1100),the edge detection scanning range is the position of (1102). Assumingthat the measuring pattern is (1104) in the hole pattern image (1103),the edge detection scanning range is (1105).

By the device of this embodiment of the present invention, theobservation magnification factor can be automatically decided bychanging the area for scanning a sample to be detected from numericalvalue information of another pattern form whose observationmagnification factor is to be changed and the most suitable scanningdirection can be automatically decided to obtain an evaluation valuefrom the pattern form.

Further, since an unnecessary electron beam is not scanned,contamination caused by an electron beam can be reduced. Since thenumerical information of the pattern form and position relationship aredetected in consideration of the edge, they are hardly affected by thecharge-up and uneven contrast which are unique to the electronmicroscope. Since the pattern form and position relationship are inputas numerical values in the registration operation, the detection of apattern as a guide requiring experience and setting of magnificationfactor are not required. Since it is not necessary to actually observe apattern on a wafer and register a template, a recipe file can beprepared offline.

The detection method of hole patterns at the magnification factor formeasuring the length will be explained by referring to FIGS. 13 and 14.The detection method inputs the parameter range corresponding to changesin the pattern form, thereby can obtain also the roundness and area ofholes. Here, the size change of the hole diameter will be explained. Thedetection method prepares a pattern mask from the hole diameter (S1301).The method scans the mask pattern for an image (4106) read into theimage memory 17 of the image processor 16, thereby calculates anevaluation value using Formula (S1302). The method stores the positionwhere the evaluation value is maximized and the evaluation value (S1303)and changes the form parameter (hole diameter in this case) (S1304).When the parameter is within the designated range, the method repeatsS1301 to S1305. The parameter position having the maximum evaluationvalue among the parameters obtained according the aforementionedprocedure is the detection position (S1306). Furthermore, themeasurement length can be calculated from the parameter having themaximum evaluation value (S1307).

Boundary lines 4108 and 4109 for specifying the parameter range may beset by numerical value input on the numerical value input screen shownin FIG. 14A or may be set on the pattern model display shown in FIG.14B. In this case, the boundary lines 4108 and 4109 displayed on thedisplay device are set by changing and moving by a pointing device notshown in the drawing.

The device of this embodiment has a function for displaying an actualSEM screen on the display device in accordance with the setting screenshown in FIGS. 14A and 14B. By this display, for example, when a patterndifferent from the design data is formed due to an error in asemiconductor manufacture device, parameter setting according to anactual objective pattern can be executed. Furthermore, when a patternmodel is also displayed on the basis of the design data (CAD data, etc.)of the semiconductor manufacture device, appropriate parameter settingcan be executed on the basis of visual comparison with precise designdata.

As mentioned above, according to the present invention, the process orinput operation relating to the template matching art used forinspection positioning so far can be reduced remarkably and a scanningelectron microscope can be operated with high precision at high speed.

1. A method for measuring patterns formed on a semiconductor wafer witha scanning electron microscope comprising steps of; scanning an electronbeam on the patterns, detecting secondary electrons emitted from thesemiconductor wafer, determining a number of patterns or an evaluationvalue of the patterns based on an image of the patterns formed by thedetected electrons, and determining whether the patterns are to bemeasured or not, based on the number of parts or the evaluation value ofthe patterns.
 2. The method for measuring the patterns formed on thesemiconductor wafer according to claim 1, further comprising step of:skipping the patterns when the number of patterns or the evaluationvalue of the patterns do not exceed a threshold regarding the number ofpatterns or the evaluation value of the patterns.
 3. The method formeasuring the patterns formed on the semiconductor wafer according toclaim 1, further comprising step of: skipping the patterns when thenumber of patterns is the same as a threshold number.
 4. The method formeasuring the patterns formed on the semiconductor wafer according toclaim 1, further comprising step of: skipping the patterns when thenumber of patterns or the evaluation value of the patterns are greaterthan a threshold regarding the number of patterns or the evaluationvalue of the patterns.
 5. A method for measuring patterns formed on asemiconductor wafer with a scanning electron microscope comprising stepsof; scanning an electron beam on a plurality of measuring positionscontaining patterns, detecting secondary electrons emitted from thesemiconductor wafer, determining, at each measuring position, a numberof patterns or an evaluation value of the patterns based on an image ofthe pattern formed by the detected electrons, and skipping a nextmeasuring position when it is determined that a shape of the patterns atthe measurement position is getting worse than the patterns at previousmeasuring position.
 6. The method for measuring patterns formed on thesemiconductor wafer according to claim 5, wherein, the next measurementposition is outside of the patterns on the semiconductor wafer.
 7. Acomputer for controlling a scanning electron microscope comprising anelectron gun, a deflector for scanning an electron beam on a sample, anda detector for detecting electrons generated from the sample by scanningthe electron beam on the sample; the computer programmed to perform asequence of steps comprising: scanning an electron beam on the patterns,detecting secondary electrons emitted from the semiconductor wafer,determining a number of patterns or an evaluation value of the patternsbased on an image of the patterns formed by the detected electrons, anddetermining whether the patterns are to be measured or not, based on thenumber of parts or the evaluation value of the patterns.
 8. The computeraccording to claim 7, the computer further programmed to perform thestep of: skipping the patterns when the number of patterns or theevaluation value of the patterns do not exceed a threshold regarding thenumber of patterns or the evaluation value of the patterns.
 9. Thecomputer according to claim 7, the computer further programmed toperform the step of: skipping the patterns when the number of patternsis as same number as a threshold of number.
 10. The computer accordingto claim 7, the computer further programmed to skipp the patterns whenthe number of patterns or the evaluation value of the patterns aregreater than a threshold regarding the number of patterns or theevaluation value of the patterns.
 11. A computer for controlling ascanning electron microscope comprising an electron gun, a deflector forscanning an electron beam in a sample on a sample, and a detector fordetecting electrons generated from a sample by scanning the electronbeam on the sample; the computer programmed to perform a sequence ofsteps comprising: scanning an electron beam on a plurality of measuringpositions containing patterns, detecting secondary electrons emittedfrom the semiconductor wafer, determining, at each measuring position, anumber of patterns or an evaluation value of the patterns based on animage of the patterns formed by the detected electrons, and skipping anext measuring position when it is determined that a shape of thepatterns at the measurement position is getting worse than the patternsat previous measuring position.
 12. The computer according to claim 11,wherein, the next measurement position is outside of the patterns on thesemiconductor wafer.